A comparison of coronal and interplanetary current sheet inclinations
- 1 October 1983
- journal article
- Published by American Geophysical Union (AGU) in Journal of Geophysical Research
- Vol. 88 (A10) , 7837-7842
- https://doi.org/10.1029/ja088ia10p07837
Abstract
HAO white‐light K‐coronameter observations show that the inclination of the heliospheric current sheet at the base of the corona can be both large (nearly vertical with respect to the solar equator) or small during Carrington rotations 1660–1666 and even on a single solar rotation. We discuss Voyager 1 and 2 magnetic field observations of crossings of the heliospheric current sheet at distances from the sun of 1.4 and 2.8 AU. Two cases are considered: one in which the corresponding coronameter data indicate a nearly vertical (north–south) current sheet and another in which a nearly horizontal near‐equatorial current sheet is indicated. For the crossings of the vertical current sheet a variance analysis based on hour averages of the magnetic field data gave a minimum variance direction consistent with a steep inclination. The horizontal current sheet was observed by Voyager as a region of mixed polarity and low speeds lasting several days, consistent with multiple crossings of a horizontal but irregular and fluctuating current sheet at 1.4 AU. However, variance analysis of individual current sheet crossings in this interval, using 1.92‐s averages, did not give minimum variance directions consistent with a horizontal current sheet. We conclude that one cannot assume that the minimum variance direction will be the same as the normal to the current sheet when the analysis results are likely to be influenced by small‐scale variations or curvatures within or near the sheet proper. This influence may be more pronounced when the sheet is locally nearly horizontal.Keywords
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